Caesar

was made by Hadrian a title, conferred on the heir presumptive
to the throne (A.D. 136). Diocletian conferred the title on the two
viceroys, calling the two emperors Augustus (sacred majesty).
The German Emperor still assumes the title of kaiser (q.v.).

Caesar, as a title, was pretty nearly equivalent to our Prince of
Wales and the French dauphin.

Caesar's wife must be above suspicion. The name of Pompeia having
been mixed up with an accusation against P. Clodius, Cæsar divorced
her; not because he believed her guilty, but because the wife of Cæsar
must not even be suspected of crime. (Suetonius: Julius Cæsar,
74.)